Molecular characterization of multi-drug-resistant Acinetobacter baumannii isolated from patients in a hospital in Yunnan

Objective To analyze phenotypes and genotypes of Acinetobacter baumannii isolated from ICU patients in a hospital in Kunming, Yunnan province. Methods A total of 28 A. baumannii strains were isolated from the patients in this hospital, and the strains were identified and their susceptibilities to 21 antibiotics were tested by using the bioMe'rieux VITEK-2 system. PCR screening and sequencing was performed to identify -lactamase genes, fluoroquinolone resistance related genes, aminoglycoside resistance related genes and gene capturing elements. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were conducted to analyze the genetic relationships among the isolates. Results Among the strains isolated, 78.6% were MDR, 14.3% were XDR and 7.1% were PDR. All the isolates were resistant not only to 1st and 2nd generation cephalosporins and most 3rd and 4th generation cephalosporins (ceftriaxone, ceftazidime and cefepime), but also to monobactams (aztreonam), quinolones (ciprofloxacin and levofloxacin), aminoglycosides (kanamycin) and nitrofurantoin (furadantin). All the isolates co-carried blaOXA genes, quinolone resistance related gene-aac(6')-Ib-cr, aminoglycosides resistance related gene-aacA4 and gene capturing element-int 1. Phylogenetic analyses by PFGE revealed that all the isolates were in one clad. Conclusion MDR A. baumannii possessing blaOXA, aac(6')-Ib-cr, and aacA4 might circulate in this hospital, it is necessary to conduct further clinical and epidemiological survey, take effective control measures and use antibiotics rationally.